Diffraction color photograph and mode of making same.



PATENTED APR. lO, 1906.

H. E. IVES.

DIEERAGTION COLOR PHOTOGRAPH AND MODE OF MAKING SAME.

APPLICATION FILED 00T. 19, 1905.

MHHAHAHANM?! fyzaermoff! Iene@ UNITED sTATEs PATENT oEEIcE.

HERBERT E. IVS, OF WOODCLIFFE-ON-THE-HUDSON, NEW JERSEY. DIFFRACTIONCOLOR PHOTGGRAPH yAND MODEIOF MAKING SAME.

No. s155569.

Patented April 10, 1906.

Application led October 19. 1905. Serial No. 2 83,481.

To allwhom, it may concern.-

Be it known that I, HERBERT E. IvEs, a citizen of the United States,residing in WoodcliEe-on-the-Hudson, New Jersey, have' invented certainImprovements in Diffraction Color Photo aphs and in the Mode of MakingSame, ofgwhich the following is a specification. I

My invention appliesA to the ,diffraction process of color hotography.In this process the colors o the photograph are due to three superposedor mixed diffraction-grating' images, each grating providing byasuitable disposition of viewing a paratus one ofthe three primarycolors.. hus in the ordin form of viewing a paratus for such pictures anarrow source o light is focused by a lens onto the eye, under whichcondition the eye observes the whole surface of the lens filled withlight. Diffraction-gratings when placed over the lens deviate anddisperse portions of the incident light t'o form spectra to right andleft ofthe central focus. 'The eye placed at any point in these spectrase'es the lenssurface evenly illuminated no longer by white light, butby lightof the color incident on the eye. If three gratings of dierentspacing are used, each (grating'sends a different color to the eye, anby a propriate s acing the three colors received y the eye the threegratings will be primary red, green, and blue. If now the-three gratingsby varying strength of the lines over their surfaces each represent thedistribution of one of the primary colors necessary to counterfeit tothe eye the form and colorjof a material object, then on so supe osingor mixing them that their combined e ect is the sum of their se arateeects they appear to the eye as a colbr photograph. These diffractioncolor photographs have heretofore been made by either of two .differentprocedures. In both the gratings images are printed on'plates of glassllowed with a solution of bichromated elatin or .albumen In accordancewith the t method the three grating rints are made one on top of theother. plate is flowed with gelatin, dried, and exposed in contact witha diraction-grating ruled on glass under a hotogra hic positive,representin by its tion o the color sensation is designed to send to theant print is which the grating eye. The resulta diffraction imagevarying in ight an shade the distribustrength according to the light andshade of the photographic image. Similar procedures With t e other twogratings and their respective positives imprint all three color recordson the same elatin surface. By the second procedure t e diffractionpicture is made up of alternate strips of each of the three spacings,the ordinary ruled gratings being replaced -by one in which the threespaoings alternate across the surface, the diffraction-lines beingparallel to the direction of the stri s. To regulate the distribution oflight an shade in printing in contact with this triple gratin a specialpositive is used ary with the three-co or record made up of alternatingjuxtaposed lines across its surface, the Image b eing projected on thetriple gratmg 'so that its lines exactly coincide with the strips of thegrating. Both of these methods have serious defects.

In making a picture in accordance with the first procedure it has beenfound by experience that the gelatin printing-surface is incapable ofreceiving with com lete success three diffraction images, for ii) twopartlyoverlapping printings are made from a gratingv the overlappingortion will fre uently be found to be less rilliant than eit er of thefree portions instead of twice as brilliant, as is necessary for thecomplete success of the process. When, moreover, severaldiffraction-gratings are superposed, they form together a new gratingwhose effects are superposed upon those of the original gratings, for rftwo gratings in which the distance apart of the ruled lines isrespectively a and b are superposed anew grating will be formed with theequivalent of a line of double strength whenever the condition m a=n t mand n whole numbers) is fulfilled. These additional coarser gratingsproduce series of spectra which are always present and mix their ef-,fects with those of the original gratings. For

example, it has been found that two gratings of two thousand andsixty-two and two thousand eight hundred and eighty-eight lines tothe`inch,whichsend,res ectively, red and blue light to the same point,fldrm a compound grating which sends green light from its fifth orderspectra to the eye at the point where the sec- 0nd order of the originalgratings is formed, showing apparentlyred and blue light mixing toproduce green instead of purple. These secondary spectra, alwayspresent, vary greatly IOO ` operation.

4mg-strip by an amount depending in strength accor-ding to the qualityof the original ruling and the conditions of printing.

They constitute anelement of uncertainty which precludes the possibilityof making the production of these pictures an exact process. f Both ofthese defects could be obviated in some degree by making the threeprintings on three separate plates of glass and superposing them; butthis method is open to the objection that the three pictures must be atdifferent distances from the eye, with consequent parallax of vision and.lack of exact agreement in position, and the necessity of: making three1prints to secure a reproduction of an origina picture and superposingthe three prints (instead of making a single print,

as canbe done when all .three of the grating images are on one surface)is likel to make the `products very irregular in qua 'ty, and is henceundesirable. It has-also been found by ex erience that no dependence canbe place on the colors obtained when the grat- 1n s overlap, even whenseparated from each ot er, pointing to the 'necessit of some method ofmimng the effects of t e gratings other than byv superposition.

The second procedure, before referred to, in which the combination ofthe effects of the different gratingpacings is rovided by havingjuxtaposed strips o eac gratin the effects being combined by the eye, isigree from the above defects, but as heretofore carried out has seriousdefects of its own. In order .for this procedure to be successful, thestrips ofeach grating-spacing should be so narrow asl to beindistinguishable as strips by the eye. The precedure adloptedheretofore makes this impracticable. e ruling of a gratin in the firstplace with alternating lines of t ee different spacings is a diiiiculta'nd laborious In usingV it, when obtained, it is` extremel diflicult toinsure the coincidence off? the co or record-lines of the positive usedwith the strips of rulings. Maklng the strips closer together wouldmcrease this diiiiculty enormously. The sli htest error would, forinstance, print part o a line of the positive corresponding to one coloron a wrong graton the relative size of the error and the wi th of thestrip. Any slight defect, such as a periodic error, present in eitherthe lines of the ositive or'the strips of grating and not in A oth alikewould cause a similar defect and theV spacing, size, and character ofthe line positive. lace restriction on the procedure. .The spacin of thepositive is de endent on the, metho lused in making it, which may makefine lines impracticable and nov reduction of the width of thecolorrecord-line of the positive in projecting its image on thebichromated gelatin can be made without a corres ondin change, oftenundesirable, in the size of t epicture.

A further objection is that due to having the grating-lines parallel tothe direction of the strips. As the strips are made narrower a factor tobe reckoned with is the possibility of frequent periodic repetitions ofthe disposition of grating-lines about the adj oinlng edges of twostrips of grating-spaces, thereby introducing extra diffraction effects.While this may never become a very serious factor,

it is an undesirable contingency, and therefore to be avoided.

The object of my advantages of the invention is to secure the method ofjuxtaposition in contradistinction to the method of superdefects of theposition, While obviating the To do this, I

above described procedure. make use of continuous atings ruled on glassaccording to the or ary method of producing diffraction-gratings inconjunction with ascreen of alternate transparent and opaque spaces,-the opaque spaces being twice the width of the transparent spaces.

In the accompanying drawings, Figure 1 is a diagram illustrative of myimproved method of making diffraction color photoaphs. Fig. 2 is anexaggerated section of a e-screen employed in carrying out said process.Fig. 3 is an exaggerated view of the three elements of adiffraction-color photograph made in accord with my invention, an

Fig. 4' is a view illustrating a modification of my invention. Y

In Fig. 1 of the drawmgs, represents an I ordinary photographicfpositive, and B a lens, formlng an image o the positive on the frontsurface of a bichromatized gelatinplate C, which is fixed rigidly inplace. D is the screen of transparent and opaque lines, mounted with amicrometer-screw or other device .by which it face of the plate C to anydesired extent, and E is a continuous diffraction-gratin on glasspressed into contact with the gelatin surface of the plate C. i

No attempt is made to illustrate proportions, as this is precluded bythelimitations im osed upon the draftsman.

thel positive A re resents the primary red, the grating E Will e onewhose spacing is calculated to send red light to the eye in the'viewingapparatus. has been made the red positiveis placed by one representingthe primary green, the linescreen D is shifted to the extent of thewidth of each of its clear s aces, the grating E is replaced by onecalcu ated to send green light to the eye, and a second exposure ismade.

"Similar procedure secures a print correspond- After an exposure may bemoved across the IIO ` the' grati v-liiies.

the three line diiiraction-pictures made up of juxtaposed stri s of anydesired degree of fineness. It is a so possible by this method to havethe lines o the line-screen run at any angle to In practice it is founddesirable to ave the lines of the line-screen at D run other thanparallel, referably perpendicular, to the lines of thediffraction-grating, so that each fphotograph Will be composed ofrepetitions o three juxtaposed strips 9;, a," and x2, Fig. 3, eachcomposed of lines representing the diiraction-rulin proper for the colorrepresented, the lines o the rulings being at right angles to thedirection of the strip. One a vantage of this is that secondarydiffractioii effects produced when the separation of the stripsis madevery small are disposed at a different angle than those roin` the atingsutilized to send the red, green,'and lue desired, and so do not producedisturbance. It is also obviousthat the dis osition of the strips atright angles to the ditlracting-lines places practically no limit uponthe width of the strips, which can be made mere rows of points, ifdesired, since the reduction of width until they are no longerdistinguishable by the eye is dependent simply upon the fineness of the'line-screen.

lit would be possible to use theopaque lined screen in connection with acomposite dii'raction-grating instead of three continuous gratings, thecomposite grating having three different s acings of lines disposed instrips, each of tliie width of the transparent spaces of theline-screen, the latter after each exposure bein moved to the extent ofthe width of one o? said spaces, so that on each exposure one of thegrating-strips `will be exposed and the other two shielded; but asidefrom the diiiiculty of making such a composite grating its usenecessitates extreme care in order to insure the accurate alinement ofthe line-screen and composite ruling. It Will also be possible topermanently combine with each diffraction-grating a line-screen havingits clear spaces disposed with reference to the color represented bysaid di'raction-grating, three of these composite line and diffractionscreens being used in succession, care being taken in each case toproperly register the composite'difiraction and line screen with thesensitive plate, so as tol insure the proper juxtaposition of thesuccessively-formed diffraction line-stri s on said plate; Suche seriesof screens is sliiown in Fig. 4, E', E2, and E3 representing the three(infraction-gratings and D D2, and D3 screens having their clear spacesin different lateral relation.

Having thus described my invention, I claim and desire to secure byLetters Patenti. The mode herein described diiiraction color photograph,said inode consisting in projecting onto the sensitive surof making aface, through three successive and differently-ruled diffractiongratings, and threev successive and different dispositions of cleaispaces in a line-screen device, rays from three successsiveiniages,jeach representing one of the primary-color sensations,substantially as specified.

2. The mode herein described of producing a diffraction colorphotograph, said inode consisting in projecting onto the sensitivesurface throu h three successive and difierently ruled iraction gratingsand three successive and different dispositions of clear spaces of aline-screen device which are disposed at an angle to thediffraction-lines, rays om three successive ima es, each representingone of the primary-co or'sensations, substantially as specified.

3. The mode herein described of producing a diffraction colorphotograph, said mode consisting in projecting onto the sensitivesurface, through three successive and differently-ruled diffractiongratings and a linescreen having opaque spaces twice as wide as' itsclear spaces, rays from three successive images, each representin one ofthe primarycolor sensations, and shi ing the line-screen, between'successive exposures to the extent of the Width of each of its clearspaces, substantially as speciiied.

4. The inode herein described of producing a diffraction colorphotograph, said mode consisting in projecting onto a sensitive surface,through three successive and continuously-ruled but differingdiiraction-gratings and three successive and different dispositions ofclear spaces of a line-screen device, rays from three successive images,eachrepresenting one ofthe primary-color sensations, substantially asspecii'ied.

5. The mode herein described of producing a diffraction colorphotograph, said mode consisting in projecting onto a sensitive surface,through'three successive andcontinuously-i'uled but differingdifiraction-gratings, and a line-screen having opaque spaces twice aswide as its clear spaces, rays from three successive ima es, eachrepresenti'nfy one of the primary-coor sensations, and shitting theline-screen between successive exposures to the extent of the Widthofeach of its clear spaces, substantially as specified.

6. The inode herein described of producing a diti'raction colorphotograph, said mode consisting in projecting onto a sensitive surface,through three successive and continuously-ruled but differingdiffraction-gratings and a line-screen having opaguespaces twice as Wideas its clear spaces and disposed at an angle to the infraction-lines,rays from three successive ima es, each representing one of theprimary-co or sensations, and shitting the line-screen betweensuccessive exposures to the extent of the Width of each of its clearspaces, substantially as speciiied.

IIO

ISO

7. A di'raotion color photograph cornname to this specieation in thepresence of iosed of juxtaosed strips of diz'raetionl two subscribingWitnesses. ines the lines o each strip beino' space dif- Y ferelitlyfrom those of the othei strips, and HERBERT E' NES' 5 being disposed atan angle to the direction of Witnesses:

the strip7 substantially as specified. A. J. GRUPE,

In testimony whereof I have signed my l CEAS. A.. NICHOLSON.

